Ammon Bundy arrives to address the media at the Malheur National Wildlife Refuge near Burns, Oregon in this January 5, 2016 file photo. Ammon Bundy, the leader of an armed occupation at a wildlife refuge in Oregon and several of his companions were arrested by federal authorities on Tuesday, CNN reportedAmmon Bundy (R) meets with Harney County Sheriff David Ward along a road south of the Malheur National Wildlife Refuge near Burns, Oregon in this January 7, 2016 file photo. Ammon Bundy, the leader of an armed occupation at a wildlife refuge in Oregon and several of his companions were arrested by federal authorities on Tuesday, CNN reported

The leaders of an armed group that has occupied a national wildlife refuge for the past three weeks have been arrested by the FBI and police in a traffic stop that sparked gunfire - and one death - along a highway through Oregon's frozen high country.

The leaders of an armed group that has occupied a national wildlife refuge for the past three weeks have been arrested by the FBI and police in a traffic stop that sparked gunfire - and one death - along a highway through Oregon's frozen high country.

Militant leader Ammon Bundy and his followers were reportedly heading to a community meeting in John Day, a town in Grant County town about 70 miles north of Burns, to address residents to discuss their views on government management of public lands.

The Oregonian newspaper said several hundred people gathered at the John Day Senior Centre and were told the "guest speakers" would not be appearing.

The FBI and Oregon State Police said agents had made eight arrests: Bundy, 40; his brother Ryan, 43; Brian Cavalier, 44; Shawna Cox, 59; and Ryan Payne, 32, during a traffic stop on US Highway 395.

Ammon Bundy (R) meets with Harney County Sheriff David Ward along a road south of the Malheur National Wildlife Refuge near Burns, Oregon in this January 7, 2016 file photo. Ammon Bundy, the leader of an armed occupation at a wildlife refuge in Oregon and several of his companions were arrested by federal authorities on Tuesday, CNN reported

Each will face a federal felony charge of conspiracy to impede officers of the United States from discharging their official duties through the use of force, intimidation or threats.

Police said troopers were involved in the traffic-stop shooting, though neither agency released details about what started it. One of those arrested, described only as a man, had non-life-threatening wounds and was treated in hospital, the agencies said.

Another man "who was a subject of a federal probable cause arrest" was killed, they said. The agencies said they would not release further information about the death until he was identified by the medical examiner.

Bundy's group, which has included people from as far away as Arizona and Michigan, seized the headquarters of the Malheur National Wildlife Refuge on January 2 as part of a long-running dispute over public lands in the West.

Officers converged on the refuge after the arrests. It was unclear how many people, if any, remained in the buildings.

The confrontation came amid increasing calls for action against Bundy for the illegal occupation of the wildlife refuge. They previously took a hands-off approach, reflecting lessons learned during bloody stand-offs at Waco, Texas, and Ruby Ridge, Idaho, during the 1990s.

Many residents of Harney County, where the refuge is located, have been among those demanding that Bundy leave. Many sympathise with his criticism of federal management policies of public lands but opposed the refuge takeover, fearing violence could erupt.

Ammon Bundy had recently begun travelling into Grant County to try to drum up more sympathy for his cause.

"I am pleased that the FBI has listened to the concerns of the local community and responded to the illegal activity occurring in Harney County by outside extremists," Oregon senator Jeff Merkley said.

"The leaders of this group are now in custody and I hope that the remaining individuals occupying the Malheur National Wildlife Refuge will peacefully surrender so this community can begin to heal the deep wounds that this illegal activity has created over the last month."

The Bundys are the sons of Nevada rancher Cliven Bundy, who was involved in a high-profile 2014 stand-off with the government over grazing rights.

The state police said it would investigate the officer-involved shooting, with help from the Deschutes County Major Incident Team and the Harney County District Attorney's Office.

The militants, calling themselves Citizens for Constitutional Freedom, came to the frozen high desert of eastern Oregon to decry what it calls onerous national land restrictions and to object to the prison sentences of two ranchers convicted of starting fires.

Specifically, the group wanted federal lands turned over to local authorities. The US government controls about half of all land in the West.